Which device measures the amount of ground movement during an earthquake?

• A. Seismometer
• B. Richter Scale
• C. Mercalli Scale
• D. Seismoscope

Answer: (A)

Seismometer measures the amount of ground movement during an earthquake. It records how the ground shakes over time, producing a reading that reflects actual motion (often in terms of acceleration, velocity, or displacement). The Richter scale estimates the earthquake’s magnitude from wave amplitudes, the Mercalli scale rates the shaking’s effects on people and structures, and a seismoscope only signals that motion happened without quantifying how much. So the seismometer is the instrument that directly measures ground movement.